1. Field of the Invention
The present invention relates to field of flywheel systems. More particularly, the present invention the relates to high speed flywheel systems. Even more particularly, the present invention relates to flywheel systems utilizing conical configurations.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
A flywheel is a mechanical device with significant moment of inertia used as a storage device for rotational energy. The flywheel has been used since ancient times, the most common traditional example being the potter's wheel. In the Industrial Revolution, James Watt contributed to the development of the flywheel in the steam engine, and his contemporary James Pickard used a flywheel combined with a crank to transform reciprocating into rotary motion. In a more modern application, a momentum wheel is a type of flywheel useful in satellite pointing operations, in which the flywheels are used to point the satellite's instruments in the correct directions without the use of thruster rockets.
Flywheels resists changes in their rotational speed, which helps steady the rotation of the shaft when a fluxuating torque is exerted on it by its power source such as a piston based engine, or when the load placed on it is intermittent. Flywheels can be used to produce very high power pulses as needed for some experiments, where drawing the power from the public network would produce unacceptable spikes. A small motor can accelerate the flywheel between the pulses. Recently, flywheels have become the subject of extensive research as power storage devices for use in vehicles.
In application of flywheels in vehicles, the phenomenon of precession has to be considered. A rotating flywheel responds to any momentum that tends to change the direction of its axis of rotation by a resulting precession rotation. A vehicle with a vertical-axis flywheel would experience a lateral momentum when passing the top of a hill or the bottom of a valley (roll momentum in response to a pitch change). Two counter-rotating flywheels may be needed to eliminate this effect.
The amount of stored rotational energy or flywheel capacity increases with the square of angular velocity according to the physical principles of kinetics. However, as a practical matter, the maximum angular velocity is limited by strength of materials considerations in order to preserve the structural integrity of the flywheel rotor. Further, efficiency considerations are important in evaluating a particular rotor. Efficiency of energy storage flywheels is expressed in terms of energy density and volumetric efficiency. As efficiency increases, rotor space and mass requirements decrease for a given quantity of stored energy. Both the maximum allowable angular velocity and the efficiency are directly related to the specific strength of the primary load bearing material of the rotor.
Various patents have issued in the past relating to flywheel technology. For example, U.S. Pat. No. 4,498,015, issued on Feb. 5, 1985 to the present inventor, describes a flywheel device for a moving vehicle. The device comprises three flywheels mounted mutually perpendicular on shafts in three dimensions within a rigid enclosure. The shafts are interconnected within the enclosure through a bevel gear arrangement in which the motion of one flywheel is imparted to the other flywheels. The shafts pass through the walls of the enclosure through a bearing arrangement.
U.S. Pat. No. 6,232,671, issued on May 15, 2001 also to the present inventor, teaches a flywheel energy storage apparatus with braking capability. The apparatus is for a vehicle having a housing resiliently mounted in the vehicle. There are three pairs of flywheels each rotatable about separate axes within the housing. An energy input mechanism is connected to at least one of the flywheels for initiating and maintaining rotational movement of the flywheels. There is an output mechanism for converting the rotation of the flywheels into potential energy. Each of the flywheels of the first, second and third pairs are rotatable in opposite directions. Each of the axes are perpendicular to each other. A cradle is connected to the vehicle so as to receive the housing within the cradle. This flywheel system is designed to be safe, yet portable, as an electro-mechanical battery.
U.S. Pat. No. 3,960,034, issued on Jun. 1, 1976 to Hintergraber, describes a flywheel with an anti-cracking safeguard for protection against overspeed. The flywheel includes a frustroconical shaft portion, a flywheel mounted in press-fitting engagement on the shaft portion. The shaft portion has a force applied thereto directed toward the end of the frustroconical shaft portion having the smaller diameter. A catching and centering device for the flywheel is located adjacent the flywheel.
U.S. Pat. No. 6,014,911, issued on Jan. 18, 2000 to Swett, teaches a flywheel with a self-expanding hub. The flywheel has a rotor and annular disk which are of a composite material. A metal hub is secured to a shaft and joined to the disk at a hoop. The hub has opposite sections which are of a generally double conical shaft. A concentric rim extends around each hub section and upon rotation the hub sections expansivity deform about the rim to apply a compressive force to the disk to maintain a substantially stress free condition at the rotor and disk interface.
U.S. Pat. No. 5,566,588, issued on Oct. 22, 1996 to Bakholdin et al., describes a flywheel rotor with a conical hub. The flywheel rotor is used in a flywheel energy storage system and provides a high energy storage capacity while providing an ample volume for a high power motor-generator within its envelope. The flywheel rotor includes an outer, primarily cylindrical body having conically tapered end sections, a conical hub section attached to the outer body, and a relatively short inner cylinder. The cylinder connects the shaft to the inner portion of the conical hub section. The individual components are predominantly constructed of filament wound fiber composites. Material choices may be driven by both cost and performance. The inner portion of the inner cylinder can be a slotted aluminum cylinder.
U.S. Pat. No. 4,844,224, issued on Jul. 4, 1989 to Fukushima, teaches a flywheel assembly. The flywheel assembly has a first flywheel and a second flywheel. The first flywheel has a supporting plate and a slidable friction plate attached to and slidable with respect to the supporting plate. There is a damping mechanism for damping vibrations resulting from the spring force and a friction damping mechanism for damping vibration resulting from the friction force and operating on clutch engagement and disengagement. A disc-shaped diaphragm spring is provided for preventing vibration of the second flywheel by connecting the damper plate of the friction damper mechanism to the friction plate which slides away from the clutch at the time of clutch disengagement.
Various patents have issued in the past concerning flywheels having multiple layered compositions. U.S. Pat. No. 4,207,778, issued on Jun. 17, 1980 to Hatch, describes an reinforced composite flywheel. The cross-ply composite flywheel has a rim portion of circumferentially wound fibers impregnated with a binder. The density-to-stiffness ratio of the rim portion is of a value substantially less than the density-to-stiffness ratio of the cross-ply central portion of the flywheel. The strength of the flywheel is enhanced and only a minimum contribution is made to the weight of the flywheel.
U.S. Pat. No. 6,247,382, issued on Jun. 19, 2001 to Dumeki et al., teaches a composite material flywheel device. The flywheel structure has a ring made from a composite material of carbon fiber reinforced plastics and a spoke member inserted in the ring. The spoke member is made from the fiber reinforced plastics having a lower modulus of elasticity than that of the ring. A tapered bush is press-fitted into a center portion of the spoke member. Both of the tapered bush and the spoke member are tightly fixed on a shaft by a first spring supported by a holder, and by a second spring urging the holder so as to effectively prevent vibrations due to looseness thereof.
U.S. Pat. No. 4,186,245, issued on Jan. 29, 1980 to Gilman, describes an energy storage flywheel. The flywheel is constructed from glassy metal alloy strips having a high specific strength comparable to anisotropic fibers used in high energy density flywheels. The glassy metal alloy strips are formed into circular layers, and a plurality of layers are joined concentrically to build up the flywheel. Joining between strips and layers is accomplished with bonding means such that a substantially mechanically monolithic composite structure results. This provides a bonding shear strength at least about equal to the specific strength times the density divided by the aspect ratio of the glassy metal alloy strips.
Various patents have also issued in the past relating to high speed flywheels. For example, U.S. Pat. No. 5,012,694, issued on May 7, 1991 to McGraph, describes such a flywheel. The flywheel utilizes two or more ring-like components arranged in a spaced concentric relationship for rotation about an axis, and an expansion device interposed between the components for accommodating radial growth of the components resulting from flywheel operation. The expansion device engages both of the ring-like components, and the structure of the expansion device ensures that it maintains its engagement with the components. In addition to its expansion-accommodating capacity, the expansion device also maintains flywheel stiffness during flywheel operation.
It is an object of the present invention to provide a flywheel system which uses a very high rotating speed in a safe manner.
It is another object of the present invention to provide a flywheel system with increased storage capacity.
It is yet another object of the present invention to provide a high speed flywheel system having a reduced mass.
It is yet another object of the present invention to provide a flywheel system that is reduced in size.
It is a further object of the present invention to provide a high speed flywheel system that enables microvibration absorption.
It is another object of the present invention to provide a high speed flywheel system with reduced vibration.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.